RAPID AND STABLE GENE-EXPRESSION IN HIPPOCAMPAL SLICE CULTURES FROM ADEFECTIVE HSV-1 VECTOR

Stable transfer of genetic information into neurons is a powerful stra tegy to elucidate specific mechanisms of neurophysiology and to develo p therapies for neurological disorders. To evaluate the optimal parame ters for efficient gene delivery of defective herpes simplex virus typ e one (HSV-1) vectors into a specific brain region, an HSV-1 vector ex pressing E. coli beta-galactosidase was used to infect organotypic cul tures of hippocampal slices. beta-Galactosidase was expressed as early as 2 h after infection in a dose-dependent manner as measured on immu noblots, and reached a maximum level after similar to 35 h. Expression of the RNA and the antigen was still evident after the longest time s ampled (11-12 days), whereas no beta-galactosidase was ever detected i n cultured slices infected with a control virus lacking the reporter g ene. Hippocampal cells expressing the reporter gene outlined the conto ur of the neuronal cell body layers in fields CA3 and dentate gyrus; s uch correspondence was less evident in field CA1. Anatomical, morpholo gical, and immunohistochemical criteria also confirmed that the majori ty of these infected cells were neurons. beta-Galactosidase was also d etected in the somata and processes of infected interneurons. Tests fo r synaptic pathology associated with virus infection showed no changes in pre- and postsynaptic markers.